Concise notation for assigning `unique_ptr`?

I have a pointer to a parent class and I want to assign a new child object to that pointer conditionally. Right now, the syntax I have is rather lengthly:

std::unique_ptr<ParentClass> parentPtr;
if (...) {  
  parentPtr = std::unique_ptr<ParentClass>(new ChildClass1());  
} else {
  parentPtr = std::unique_ptr<ParentClass>(new ChildClass2());  
}

Is there a good way of making this more readable / less lengthly?